This invention relates generally to rotating machine technology, and specifically, to the mounting of compressor blades in rotor dovetail slots.
Typically, wear coatings are applied to the dovetail portions of compressor blades in order to reduce compressive stresses and wear between the blades and the compressor wheel dovetail slots. Such coatings have been applied to the blade dovetails primarily due to the fact that coatings are easily applied here. In practice, for example, the blade itself is masked, and there is a direct line of sight for spraying the coating on the blade dovetail and if curing is required, the blades can be easily handled and moved through an oven. Some typical wear coatings, however, such as MoS2 and other generally similar coatings, are not compatible with a typical steel C450 alloy used for the blades. In fact, coatings applied to C450 alloy material can degrade the corrosion fatigue resistance of that material.
Accordingly, there remains a need to provide wear resistance between compressor blades and compressor wheel dovetails without jeopardizing the corrosion fatigue resistance of the blade.